Clojure/Nim Architecture

Overview

Clojure/Nim is a compiler, not an interpreter. It follows the model of ClojureScript: Clojure source is read, macro-expanded, analyzed, and emitted as Nim source code, which then compiles to C and finally to a native binary.

Compilation Pipeline

┌─────────────┐
│  .clj File  │
└──────┬──────┘
       │
  ┌────▼────┐
  │ Reader  │  ← EDN parser. Produces Clojure data structures.
  └────┬────┘
       │
  ┌────▼────┐
  │ Macros  │  ← defmacro expansion. Operates on Clojure data.
  └────┬────┘
       │
  ┌────▼────┐
  │ Analyzer│  ← Special forms, locals, closure analysis.
  └────┬────┘
       │
  ┌────▼────┐
  │ Emitter │  ← Generates Nim AST / source code.
  └────┬────┘
       │
  ┌────▼────┐
  │ Nim CC  │  ← Nim → C compilation.
  └────┬────┘
       │
  ┌────▼────┐
  │   C CC  │  ← C → machine code (GCC/Clang).
  └────┬────┘
       │
  ┌────▼────┐
  │  Binary │  ← Single native executable.
  └─────────┘

Key Design Decisions

1. AOT Compiler

We compile ahead-of-time, like ClojureScript. This gives us:

Fast runtime execution (C speed)
Small binary size
No interpreter overhead

The trade-off is that REPL compilation is slower (each form is compiled individually).

2. Clojure Macros on Clojure Data

Macro expansion happens before reaching Nim. Nim never sees Clojure macros:

(defmacro unless [condition & body]
  `(if (not ~condition)
     (do ~@body)))

This macro operates on CljVal objects (Clojure lists, symbols), not Nim AST.

3. Runtime in Nim

The lib/cljnim_runtime.nim module provides:

CljVal — tagged union representing all Clojure values
cljAdd, cljMul, etc. — polymorphic arithmetic
cljRepr — string representation

4. Nim Interop (Future)

Instead of Java interop, we will have Nim interop:

(nim/import "strutils")
(nim/call "strutils.join" ", " ["a" "b"])

Module Responsibilities

Module	Role
`src/reader.nim`	Parses `.clj` text into `CljVal` AST
`src/emitter.nim`	Transforms `CljVal` AST into Nim source
`src/repl.nim`	Human and AI REPL implementation
`src/types.nim`	AST node types (used by reader/emitter)
`src/macros.nim`	Macro expansion engine
`src/runtime.nim`	Additional runtime helpers
`lib/cljnim_runtime.nim`	Core runtime library

Memory Model

Uses Nim's ORC garbage collector
CljVal is a ref object (heap-allocated)
Future: persistent data structures use structural sharing

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